In the continuing pursuit of ways to reduce the weight and also the fuel consumption of motor vehicles, it has already been suggested that plastic be used to produce various components of a vehicle body that are conventionally made from metal. A proposal for a roof panel manufactured mainly from a fiber-reinforced plastic is known for example from DE 10 2008 032 334 A1. This roof panel with a substantially flat cross section, at least in the direction transverse to the vehicle, is supported along the side edges thereof by horizontal flanges of two longitudinal lateral roof support members and fixed to the lateral sides of the longitudinal roof support members with adhesive beads.
Since plastics generally undergo considerably greater thermal expansion than metals, the expansion behavior of these conventional roof panels differs significantly from that of the metal longitudinal support members to which it is fastened. Consequently, significant compression and shearing forces occur in the adhesive beads, and over time these can cause the adhesive bond to fail.